Can be made on the fly out of any suitable scrap and a knife.
Potential for cooler version if you're in to bending rods, machining or woodworking.
Mine was a hiking staff project (hence the crazy carving) in a past life but the hand grip was too thick for the intended user.
1. Your stick needs to be thick enough to take up a major portion of the triangular space between the chain stays and the rear tire. Too much play and your kickstand becomes more of spontaneous booby trap. Also don't cut your stick to length until the very last. Too long is good for now - too short bites.
2. Flip your bike upside down and place the stick between the rear tire and the chain stays. Give some thought about how it will fit before making any cuts.
3. Use a pencil to mark where your topmost groove will go and carve with a sharp knife (or in my case a reciprocating saw). This groove lays on the chain stay nearest the derailleur. Trim any excess stick that presses against the derailleur components.
4. While chain stay is resting in the first groove, angle your stick until it securely wedges between both chain stays and the rear tire. Mark your second cut tracing the chain stay opposite the derailleur. Remove and cut your second groove.
5. Tweak the grooves as needed to get a good fit.
6. With your stick firmly in the "kickstand down" position mark an angled cut an inch or so below a line between the bottoms of your tires. After testing if you decide you want more lean just lop off another inch.
7. Flip the bike rightside up. From the side opposite the front derailleur lean the bike away from you and insert your stick into the now cozy triangle formed by rear tire and the chainstays. Lean the bike towards you and check for a firm fit.
8. Check once again that your stick isn't pressing against any delicate components and trim as needed. Check that your bike is stable. If you really botched it you're only out a stick and 10 minutes - start over a little bit wiser than before.
1. You could file down the grooves or even pad them with felt, neoprene or inner tube scraps.
2. Find a forked stick and you have a workstand that raises your rear wheel. (I'll write that up as soon as I find the right forked stick.)
3. A scrap of plywood (or similar) glued or screwed to the bottom would make a handy "foot" for muddy or sandy conditions.
4. Your grooves will probably NOT be parallel but rather angle towards the front of the bike (as do the chainstays).
5. A third groove for your tire might make it super stable - go for it.